1. Field of the Invention
The present invention relates to a liquid supply member for supplying liquid to a liquid discharge head which discharges liquid, a manufacturing method of a liquid supply member, a liquid discharge head for discharging liquid, and a manufacturing method of a liquid discharge head.
2. Description of the Related Art
As a liquid discharge head for discharging liquid to be recorded on a recording medium, an ink jet recording head for discharging ink is known. A liquid supply member has a supply path for supplying liquid to a discharge port which discharges liquid and is used for, for example, an ink jet recording head.
FIGS. 9A to 9C are diagrams illustrating a configuration of a conventional ink jet recording head.
FIG. 9A is an exploded perspective view of the conventional ink jet recording head. An ink jet recording head H1001 illustrated in FIG. 9A includes a tank holder unit H1003 and a recording element unit H1002. The tank holder unit H1003 includes a tank holder H1500 and a supply path plate H1600 which are joined to each other. FIG. 9B illustrates a joining surface of the tank holder H1500, and FIG. 9C illustrates a joining surface of the supply path plate H1600. The supply path plate H1600 is provided with a groove H1601 such that the vicinity of the groove H1601 becomes a welding surface H1602 to be welded to the tank holder H1500 (see FIG. 9C). When the tank holder H1500 and the supply path plate H1600 are joined to each other, the groove H1601 functions as a supply path. As ink passes through the supply path, the ink is supplied to the recording element unit H1002. As a joining method of the tank holder H1500 and the supply path plate H1600, a method using ultrasonic welding is disclosed in Japanese Patent Application Laid-Open No. 2007-283668, and a method using laser welding is disclosed in Japanese Patent Application Laid-Open No. 2005-096422.
In the joining method disclosed in Japanese Patent Application Laid-Open No. 2007-283668, a tank holder and a supply path plate are molded from a resin material. In addition, a welding surface of the supply path plate is provided with an energy director which is a projection for uniformly welding the supply path plate and the tank holder. In this joining method, the tank holder and the supply path plate are overlapped at a predetermined position and fixed, and when ultrasonic vibration is applied from a side of the supply path plate, ultrasonic vibration is focused on the energy director. Accordingly, the resin of the tank holder and the supply path plate in the vicinity of the energy director is melted, such that the tank holder and the supply path plate are welded to each other. As a result, a supply path is completed.
On the other hand, in the joining method disclosed in Japanese Patent Application Laid-Open No. 2005-096422, a supply path plate is molded from a resin material which has a property of being transparent to a laser beam, and a tank holder is molded from a resin material which has a property capable of absorbing a laser beam. In this joining method, the tank holder and the supply path plate are overlapped at a predetermined position to be fixed, and the vicinity of a supply path is irradiated with the laser beam from a side of the supply path plate. Then, a surface of the tank holder irradiated with the laser beam is heated and melted, such that the tank holder and the supply path plate are welded to each other. As a result, an ink supply member having the supply path is completed.
The above-mentioned ink supply member (liquid supply member) is generally produced by mold forming in which resin is flown into a mold to be formed. On a surface of the ink supply member produced by mold forming, typically, unevenness of about 0.1 to 10 μm exists. When the unevenness exists, small bubbles are easily generated during filling of ink and thus are obstacles to enhancement of ink filling ability. Moreover, the enhancement of ink filling ability mentioned here is to suppress small bubbles from being incorporated into ink and reaching a discharge port when the ink is filled in the entire supply path.
When the ink filling ability is degraded, small bubbles easily reach the discharge port of an ink discharge part during printing, so that there is a possibility that printing errors frequently occur. To prevent this, it is thought that the unevenness of a surface of the mold is formed to be equal to or smaller than 0.1 μm to reduce a surface roughness of the ink supply member and suppress the generation of bubbles. However, in this case, adhesion between the mold surface and the ink supply member is increased. Therefore, when the ink supply member is separated from the mold, the ink supply member may be damaged, and there is a concern that the supply path having a desired shape cannot be formed with high precision.